Mechanical stoker for furnaces



March 24, 1936. J wYNN, JR 2,034,890

MECHANICAL STOKER FOR FURNACES Filed Jan. 7, 1931 6 Sheets-Sheet llllllll \\|\\\\\\\\\\\l lll lllllllll l' ffl.

March 24, 1936. N, R 2,034,890

MECHANICAL STQKER FOR FURNACES Filed Jan. 7, 1931 e Sheets-Sheet 2 86yimb gg/gf;

March 24, 1936. J. WYNN, JR 2,034,890

.MECHANICAL STOKER FOR FURNACES Filed Jan. 7, 1931 6 Sheets-Sheet 5March 24, 1936. J. WYNN, JR 2,034,890

MECHANICAL STOKER FOR FURNACES Filed Jan. 7, 1931 6 Sheets-Sheet 6 thefurnace is installed. o

Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE 2,034,890 MECHANICALs'roK R FOB- FURNACES John Wynn, Jr., Canton, Ohio Application Januaryv, 1931, Serial No. 507,095

5'Claims. (cl. 110-45 The invention relates to stokers and moreparticularly to an underfeed stoker arranged to automatically carryfuelfrom a coal bin or the like and deliver the same to the fuel chamberof a furnace at the proper rate of speed to produce the desiredtemperature within a building in which An object of the improvement'isto provide a stoker of this character including a mechanically drivenconveyer screw which may be fed by an agitating feeder leading from thebottom of a coal bin or the like to a point intermediate the bin andfurnace, a second screw located above the same being arranged to carrythe fuel from this point through a fuel chamber having air forcombustion discharging thereinto' and thence to the grateof the furnace,whereby a block of fuel is always maintained between the first andsecond screw conveyors, preventing gases or products of combustion frompassing backward through the intense heat on this side of the co bustionchamber in order to burn the smoke d unburned gases of combustion beforethey pass to the stack flue.

A further object is to mamin'a relation between the height of the tuyereabove the grat and the width of the air duct surrounding the fuelchamber to prevent excessive clinkering of the fuel upon the grate. w

Another object is to provide means for mounting the motor which drivesthe mechanism on top of the housing surrounding the inner fuel chamherat the charging end of the second or upper screw conveyer.

Another and very important object is the provision of a ring gearjournaled around the fuel passage between the two screw conveyerswhereby both conveyers may be driven from the same source of power andthe lower .conveyer may be swung around the axis of the ring gear to belocated at any necessary or desired angle to the upper conveyer, andpermitting the feeding of the fuel through the center bf-the ring gearfrom the lower conveyer to the upper conveyer.

A further object is to provide a. normally closed check draft or damperin the air duct arranged to prevent a natural air draft through the airduct from burning-out the fire around the tuyere but adapted to beautomatically opened by the pressure of air when the fan is operated. as

Another object is the provision of a chamber and above thecharging endof the upper screw to accommodate a surplus storage of fuel.

A still further object is the provision ofa feeding, agitatingandcsizing mechanism in coal bin'adapted to deliver fuel of propersizeto the 5 conveyer mechanism.

A still further object of the improvement is to provide a constructionof blower fan which will operate with a minimum amount of noise.

The above and other objects which will appear 10 from the followingdetail description of the invention and an inspection of theaccompanying drawings may be attained by constructing the stoker in themanner illustrated in the drawings.- in which I Figure 1 is a sectionalview through the lower portion of a furnace provided with the improvedstoker, showing the location of the feed mechanism within the coal bin;7

Fig. 2, a plan view of the samepartly in section; 20

Fig. 3, an enlarged plan viewof the tuyere and grate showing theconnection of the conveyor and air duct thereto;

Fig. 4, a vertical section on the line 4-4, Fig.8;-

. Fig. 5, a vertical sectional view through the co- 25 operating endportions of the two conveyer screws, illustrating the ring gearsurrounding the fuel passage between the screws and showing the motorand blower fan;

Fig. 6, a; transverse vertical section on the line 6-6, Fig. 5;

Fig. '7, a section through the blower housing showing the blower fanwith parts broken away; Y Fig. 8, a, plan view of the fuel feeding,agitating and sizing mechanism in the coal bin; i

Fig. 9', a. vertical sectional view of the same;

Fig. 10, a vertical sectional view of a modified form of feeding,agitating and sizing mechanism;

Fig. 11, a plan sectional view taken on the line to llF-l I, Fig. 5.

Similar numerals refer to similar parts throughout the drawings. a

.A portion of the combustion chamber of the furnace is shown generallyat iii, the usual to pit being located beneath the same as indicated atH. The furnace may be of any-usual and well known construction and forthis reason only the lower portion of the same is"illustrated in orderto show the application of 'the improved so stoker theretoa Theinvention contemplates the feeding of .the fuel, which maybe slack,finely divided coal or the like,'directly from thecoal bin to the fur-,mace, and for this purpose a conveyor screw I2 65 extends into thebottom of the coal bin, being located within a housing l3 having anopening II in its upper portion at the end located within the coal bin.

In order to feed thefuel from the coal bin into the housing 3, areciprocating plate I5 is mounted above the opening ll of the housingand provided with a slot or aperture l6 through which coal may pass fromthe bin downward into the housing i3. If desired, one or more pivotedhooks l1 may be carried by the reciprocating plate I5 for raking thefuel onto the plate as the sameis moved back and forth within the coalbin.

For the purpose of reciprocating the plate I5 as the conveyor screw I2is operated, a gear |8 may be fixed upon the shaft of the conveyer l2and arranged to mesh with a gear I9 pivoted upon a countershaft 28 andhaving a connecting rod 2| eccentricaily mounted thereon as by the wristpin 22, said connecting rod being pivotally connected to a pin 23 uponthe depending ear 24 fixed to the under side' of the reciprocating platel5.

The other end of the countershaft 20 may have a crank arm |9a fixedthereto, a connecting rod 2|a being connected at one end to the crankhousing. The conveyer screw I2 is journaled in this housing, as at 21,and is arranged to feed the fuel upward into the passage 26 in order toform a block or slug of fuel therein for preventing gases and smoke fromthe furnace from passing backward through the conveyer housing and intothe coal bin.

' A cast housing 3| is journaled upon the cylindric neck 32 of and,communicates with the housing 25, having an-annular shoulder 33 restingupon the upper edge of said cylindric neck.

The motor 34 is mounted upon the top ofthe casting 3|, being thus spacedconsiderably above the cellar fioor where it is away from the dirt anddust which may accumulate upon the floor and can be easily inspected. Bythus mounting the motor above thiscasting the same will not be harmed inthe event water-gets into the cellar.

The motor shaft may be'connected, as through a coupling 35, with theshaft 36 of a worm 31 Journaled as in the roller bearings 38 mountedwithin a gear housing compartment 39 which may form a part of thecasting 3|.

' The outer end of the worm shaft 36 extends into the fan casing 48which may be connected to each of the tangential portions 45, thus form:

ing a radially disposed air passage 41 extending 'from the center of themoth the periphery thereof. These radial air passages may be aosasooered by a web or plate 48 provided with a central opening 49 registeringwith the inlet opening 42 of the fan casing and exposing the curved ribs44 of the fan. Ii"

For the purpose of preventing a back lash of air into the segmentalpockets 50 as they pass the outlet port 5| of the fan casing, anarcuate' rim 52 may beformed around the periphery of the disk bodyportion of the fan covering eachof thesesegmental pockets.

Y The worm 31 meshes with aworm gear 53.

tudinally slidable sleeve 56 provided with the gear 51 and pinion 58fixed to opposite ends thereof.

For the purpose of slidably moving this sleeve upon the shaft, a rockershaft 59 may be located through the gear housing 39 and provided witharms 60 which engage studsjl' upon a yoke 62 carried by the sleeve.

A worm shaft 63 is located below and parallel with the shaft 54 and maybe joumaled in roller bearings 64 carried in the end walls of the gear.housing, A pinion 65 and a gear 66 are fixed upon the worm shaft andadapted to be engaged by the "gear 51 and pinion, 58 respectively,depending upon the position to which the sleeve 56 is moved. 7

The worm 68 upon the shaft 63 meshes with the worm gear 69 upon theshaft 10 of the upper conveyer screw 1|, one end portion of whichextends into the casting 3|, above the vertical passage 26 of thelowerconveyer screw housing. The casting 3| may be enlarged above this end ofthe upper screw conveyer 1| to provide a surplus fuel storage chamber 12above the'charging end of the upper screw.

An eccentric disk or wheel I3 may be mounted upon the shaft 10 and theeccentric ring 14 surrounding the same is provided with an arm I5pivotally connected at its outer end, as at I6, to a rocker arm 'I'Ifixed upon the rocker shaft 18 which is journaled through the casting 3|and extends into the furnace for operating the grate, as will be laterdescribed.

A bvel gear 19 is fixed upon the shaft Ill and meshes with a doublebeveled ring gear 86 journaled upon the annular neck .32 of the lowerconveyer screwhousing. A bevel gear 8|, similar to the gear 19, is fixedupon the shaft of the lower conveyerscrew |2, being located in a gearhousing'82 formed upon the lower casting 25, said bevel gear alsomeshing with the ring gear 86.

With this construction the upper and lower conveyer screws II and I2respectively are both driven at the same speed and in the samedirection.

A cylindric housing 83 surrounds the upper conveyer screw 1| and leadsfrom the casting 3| to the furnace, extending through the side wallthereof and communicating with the angular I neck 84 upon the verticallydisposed cylindric chamber 85 which is surrounded by the air chamber 86,the outer wall of which may be provided with a peripheralshoulder 81spaced from its upper end upon which the annular grate 88 is mounted foroscillatory movement.

By providing. the lower conveyer |2 for feeding fuel collected from thefloor of the fuel bin,

and the upper conveyer 1| for feeding fuel from the lower conveyer tothe-tuyere, horizontally disposed conveying means is provided forfeeding fuel directly from the ordinary bin, which is nor-' mallylocated at the floor level of therbiiilding i n which the stoker is to binstc dz jnd delivering chamber so.

The height of the tuyere above these walls should not exceed the widthof the air passage "86, this being for the purpose of preventingsufficient ash from accumulating on the grate toproduce any considerableamount of clinker thereon.

x'l'he inner portion of the tuyre is provided with openings 90communicating with the air passage 86 for discharging air for combustioninto fuel passing through the .chamber 85 beneath the top surface of thefuel, these openings being located closer together upon the flue side ofthe furnace, as indicated at 9|, than upon the opposite side 'in orderto provide an increased air area on the flue side of the furnace for thepurpose of consuming smoke and gases of combustion before they pass tothe chimney fiue.

The rocker shaft l8 extends into the furnace as best shown in Figs. 2,3, and 4 and has fixed thereon a rocker arm 92 connected as by a. link93 with a-radial finger 94 upon,the grate whereby the rocking of theshaft 18 will oscillatethe grate to shake the ashes therefrom into theash pit II.

A plate 95 may be mounted in the furnace above the ash pit and providedwith a depending annular flange 96 surrounding the grate, substantiallycutting off the ash pit from the combustion chamber of the furnaceexcepting through the open: ings in the grate.

A conduit 91 leads from the exhaust port 5| of the fan housing to theair chamber 86 and for the purpose of preventing a natural draft frompassing through this conduit and burning out the fire too rapidly aroundthe tuyere, when the fan. is not in operation,a check draft or damper 98is located within the conduit 91, being preferably pivoted at its upperportion, as indicated at 99,

as shown in Fig. 1.

When the fan is operated, the air blast will and adapted to normallyhang in closed position,

automatically swing this .check draft into open position to permit theair blast to pass through the conduit 91 but it willbe seen that when;the fan is shut off the check'draft 98 will return to closed position bygravity, preventing passage of a natural draft of airthrough theconduit.

The feeding, agitating and sizing mechanism in the coal bin may, ifdesired, be of the construction shown in Figs. 8 and 9 of the'drawingsin which the lower conveyer screw housing l3 communicates at itscharging end with a trough l3b located within the ,coal bin,the conveyerscrew l 2' being located within said trough and journaled through abearing I at the end portion of the trough. v

A bevel pinion l BI is fixed upon the shaft of the conveyer screw l2 andmeshes with a bevel gear I02 mounted upon the vertical shaft I93journaled at its lower end in a bearing I04 and at its upper end in abearing I05 carried in the cast housing I06 located beyond thetroughl3b.

An arm I0! is fixed upon the upper end of the shaft I03 and may beprovided with a roller I08 located within a radial slot )9 formed in theoscillating feeding, agitating and sizing no,

a cover portion I ll being preferably formed in ra1ity of openings 1 soarranged and located that they will remain over the trough lib in allpositions to which the disk 0 is oscillated.

These apertures I M are of such size that particles of fuel of excessivesize are not allowed to enter the trough l3.

By providing the upper casting 3| journaled upon the lower casting 25with the ring gear 90 journaled therebetween for engagement with thebevel pinions 9| and 19 of the lower and upper conveyer screwsrespectively, it will be seen that the two vertically spaced conveyerscrews and their housings may be adjusted to any desired angle withreference to each other without in any way interfering with theoperation of the mechanism," thus permitting the apparatus to beinstalled regardless of the relative locations of the furnace and coalbin.

It will also be seen that with this construction the fuel is fedupwardfrom the lower conveyer screw to the upper conveyer screw throughthe inside of the ring gear, thus permitting any desired adjustment aswell as the operation of the ring gear at all times withoutinterference.

The apparatus does not necessarily operate continuously but ispreferably controlled by a thermostatic deviceof any .usual and wellknown construction adapted to start the operation of the motor when the.house temperature falls below a certain predetermined point and to stopthe operation of the motor when the house temperature rises to thedesired point. This thermo-. static device, however, forms no part ofthe in-.

vention and is merely connected to the stoker iniusual and well knownmanner for the purpose of convenience.

In the operation of the apparatus, when the motor is started, thefeeding, agitating and sizing mechanism within the coal bin will operateto feed coal from the fioor of the coal bin to the lower conveyer screwl2 which will feed the same forward through the conduit l3 and thenupward through the vertical chamber 26 to the upper conveyer screw ll.It will be seen that the chamber 26 must necessarily be filled withfuelbefore the conveyer screw ll can carry fuel forward/to .the

furnace, tlYus providing a solid block or plug of.

' fuel in the chamber 26, between the two conveyer screws, at a pointremoved from the furnace, preventing smoke and gases of combustion fromthe furnace from passing backward through bin. i

It will also be seen that the-chamber 12 provides room for surplusstorage of fuel above the conveyer screw H as well as providing a gasand smoke pocket for any smoke or gases of combustion which may passthrough the upper conduit 83 from the furnace. i

As the fuel is fed forward through the upper the lower conveyer screwconduit l3 into the coal conduit 83, by means of the upper conveyerscrew 1 l it will be delivered to the chamber 85 at .a point spacedconsiderably above the floor of the fuel bin, and since the chamber 85communicates with the tirvere, the fuel will 'be fed upward through thechamber 85 and over the tuyre chamber 86, from' which it willdischargethrough the openings 90, in the tuyere into the upwardly movingfuel column beneath the top surface thereof, furnishing sufficient airfor combustion of the fuel.

The rocker shaft 18 will also be operated during the operation of themotor to oscillate the grate 88, shaking the ash therefrom into the ashpit ll.

When the operation of the motor is stopped, all of the moving parts willstop movement and the'check draft 98 will automatically return to closedposition, preventing a natural draft of air through the conduit 91. I

It will of course be understood, that in order to provide a practicalapparatus for the purpose for which this invention is intended, all ofthe housings between the furnace and the coal bin should be entirely gastight in order that no gases or smoke may leak therethrough into thebasement or other room in which the stoker is located. 7

I claim:

1. An underfeed furnace structure including an upwardly opening fuelchamber surrounded by an annular air chamber having means fordischarging air therefrom into the fuel contained in the fuel chamberbeneath the top surface thereof, means for supplying air under pressureto said air chamber, and means for feeding fuel upwardly through andover the top of said fuel chamber, said fuel feeding means includingvertically spaced substantially horizontal conveyers, the upper conveyercommunicating at one end with said fuel chamber, the lower conveyercommunicating at one end with a fuel bin, and-the I other ends of theconveyers being adjacent, and

a housing into which the said adjacent ends extend whereby the fueldelivered from the lower conveyer passes upwardly through said housinand forms an air seal between said conveyers.

2. An underfeed furnace structure including an upwardly opening fuelchamber surrounded by an annular air chamber having means fordischarging air therefrom into the fuel contained in the fuel chamberbeneath the top surface thereof, means for supplying air under pressureto said air chamber, and means for feeding fuel upwardly through andover the top of said fuel chamber, said fuel feeding means includingvertically spaced substantially horizontal screw conveyers, the upperconveyer communicating at one end with said fuel chamber, the lowerconveyer coirmiunicating at one end with a fuel bin, the other ends ofthe conveyers being adjacent, a housing into which the said adjacentends ex- .tend whereby the fuel delivered from said lower conveyerpasses upwardly through said housing and forms an air seal between saidconveyers, a

. 2,034,890 draft as and discharging an air blast into the air ring gearjournalled around the housing, and a pinion on each screw conveyermeshing with said ring gear.

3. An underfeed furnace structure including an upwardly opening fuelchamber, walls forming an air chamber surrounding the fuel chamber andcommunicating therewith below the top surface thereof, means forsupplying air under pressure to said air chamber, and conveyermechanism-including a housing located at a point between the furnace anda source of fuel supply, a substantially horizontal conveyer leadingfrom the source of fuel supply to said housing, a second housingjournalled upon the upper end of the first housing and communicatingtherewith,

and a second substantially horizontal conve er leading from said secondhousing to the uel chamber, whereby fuel from the lower conveyer is fedupwardly through said housings to form an air seal between theconveyers.

4. An underfeed furnace structure including an upwardly opening fuelchamber, walls forming an air chamber surrounding the fuel chamber andcommunicating therewith below the top surface thereof, means forsupplyin air. under pressure to said air chamber, and conveyer mechanismincluding a housing located at a point between the furnace and a sourceof fuel supply, a substantially horizontal conveyer screw leading fromthe source of fuel supply to said housing, a second housing journaledupon the upper end of the first housing and communicating therewith, asecond substantially horizontal con= veyer screw leading from saidsecond housing to the fuel chamber, whereby fuel from the lower conveyeris fed upwardly through said housings ing with the ring gear.

5. An underfeed furnace structure including I an upwardly opening fuelchamber, walls form ing an air chamber surrounding the fuelchamher andcommunicating therewith below the top surface thereof, means forsupplying air under pressure to said air chamber, and conveyer mechanismincluding 'a housing located at a point between the furnace and asourceof fuel supply, a substantially horizontal conveyer leading fromthe source of fuel supply to said housing, a second housing journalledupon the upper end of the first housing and communicating therewith, asecond substantially horizontal conveyer leading from the second housingto the fuel chamber, whereby fuel from the lower conveyer is fedupwardly through said housings to form an air seal between theconveyers, and said second housing forming a fuel storage chamber abovesaid second horizontal conveyer screw.

JOHN WYNN, JR.

